The unwanted and illegal video recording (camcording) in theatres projecting digital cinema content adversely affects the authorship rights of movie creators, and also the business of production studios and theatre chains. Different methods exist to protect against (combat) illegal recording (camcording), but some of them are intrusive for the audience, others (such as laser-based methods) are dangerous for the movie viewers, or have doubtful efficiency.
A number of attempts to technically prevent the video recording (camcording) in movie theatres have been described. So far there is no recognized technology that satisfies this need. Also, with the advent of Digital Cinema (DC), techniques of watermarking were created. Watermarking detection recognizes in which theatre the recording (camcording) occurred but will not be able to obstruct illegal video image capturing. That is, with the aid of watermarking detection techniques and a copy of the pirated content, it is possible to determine when and where the pirated copy was recorded (captured). The accused pirate must still be captured and then it becomes a legal matter as to conviction and punishment. In the alternative or additionally, the content distributor may approach the operator of the theatre at which the alleged pirated copy was recorded and demand increased security. It would be far easier and more efficient to discourage piracy by rendering the pirated copy unpleasant or irritating to view (watch) during rendering (displaying) of the content. The difficulties come from the fact that the viewing in the theatre may be affected by the protecting tools—the picture could be degraded, or the audience could be exposed to unwanted light flashing and beaming, e.g., if lasers were used.
There are four categories of anti-piracy methods, to which the method of the present invention could be compared:    1) Methods for locating and blinding an illegal used camera. These methods are using a scanning light beam, transmitted from the main screen area towards the audience, and reflected back from shiny objects. Reflection from camera parts and lenses is received and analyzed for detection of the illegally used camera location. Once the intrusive camera is detected, a light beam is directed to its lens, obstructing the capture of the movie (video, digital image content). The advantage of this category of methods is rendering the illegally recorded image useless. One disadvantage of the approach is non-conclusiveness in locating the camera in the audience—any shiny object (e.g. earrings) could reflect the light beam. Also, there is a danger the beam may scan and locate eye glasses (shiny objects) and direct the light beam toward the eye glasses.    2) Methods for projecting invisible light from the screen to the whole audience, which would disturb the acquisition functions of any illegal camera. This approach relies on the extended optical sensitivity of the illegal used camera in ultra-violet and in infra-red directions (ranges), and the Human Visual system perception of moving light. The advantage of this category of methods is the safety for the viewers. The disadvantage is the possibility of defeating the approach by installing optical color filter in front of the camera lens to block the thrown light.    3) Methods for adding extra frames to the projected digital image sequence, which would become visible in the illegal recorded video content. The advantage of this category is that there is no need to install equipment in the digital cinema theatre for anti-piracy protection. The disadvantage is the possibility for some viewers to perceive the additional video frames, which are not related to the subject of the movie.    4) Methods for interposing interfering sources between the projector and the projection screen, which would create temporal beat frequencies. The advantage is that the illegally used camera (camcorder) may capture the beat frequencies and its picture will be degraded. The disadvantage is that the audience will also perceive the disturbances.
It would be advantageous to have a safe and efficient method for anti-piracy, which creates enough disturbances on the digital cinema but does not decrease the quality of digital cinema viewing.